reverted:
--- b/core/modules/node/css/node.admin.theme.css
+++ a/core/modules/node/css/node.module.css
@@ -1,6 +1,6 @@
 /**
  * @file
+ * Styles for administration pages.
- * Styles for node administration.
  */
 
 /**
@@ -9,11 +9,14 @@
 
 /* Narrow screens */
 .layout-region {
+  box-sizing:         border-box;
-  box-sizing: border-box;
 }
 
 /* Wide screens */
+@media
+  screen and (min-width: 780px),
+  (orientation: landscape) and (min-device-height: 780px) {
+
-@media screen and (min-width: 780px), (orientation: landscape) and (min-device-height: 780px) {
   .layout-region-node-main,
   .layout-region-node-footer {
     float: left; /* LTR */
@@ -47,7 +50,7 @@
   .layout-region-node-secondary .form-number,
   .layout-region-node-secondary .form-color,
   .layout-region-node-secondary textarea {
+    box-sizing:         border-box;
-    box-sizing: border-box;
     width: 100%;
     max-width: 100%;
   }
@@ -59,7 +62,9 @@
  * toolbar is on, we need to suppress layout for the original media width + the
  * toolbar width (240px). In this case, 240px + 780px.
  */
+@media
+  screen and (max-width: 1020px) {
+
-@media screen and (max-width: 1020px) {
   .toolbar-vertical.toolbar-tray-open .layout-region-node-main,
   .toolbar-vertical.toolbar-tray-open .layout-region-node-footer,
   .toolbar-vertical.toolbar-tray-open .layout-region-node-secondary {
@@ -68,26 +73,3 @@
     padding-right: 0;
   }
 }
-
-/* node preview conttainer is places*/
-.node-preview-container {
-  position: fixed;
-  z-index: 499;
-  width: 100%;
-  padding: 10px;
-}
-
-@media only screen and (min-width: 36em) {
-  .node-preview-container .form-type-select {
-    margin-left: 25%; /* LTR */
-  }
-  [dir="rtl"] .node-preview-container .form-type-select {
-    margin-right: 25%;
-    margin-left: 0;
-  }
-}
-
-/* revision color */
-.revision-current {
-  background: #ffc;
-}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/node/css/node.admin.theme.css
@@ -0,0 +1,93 @@
+/**
+ * @file
+ * Styles for node administration.
+ */
+
+/**
+ * Node add/edit form layout
+ */
+
+/* Narrow screens */
+.layout-region {
+  box-sizing: border-box;
+}
+
+/* Wide screens */
+@media screen and (min-width: 780px), (orientation: landscape) and (min-device-height: 780px) {
+  .layout-region-node-main,
+  .layout-region-node-footer {
+    float: left; /* LTR */
+    width: 65%;
+    padding-right: 2em; /* LTR */
+  }
+
+  [dir="rtl"] .layout-region-node-main,
+  [dir="rtl"] .layout-region-node-footer {
+    float: right;
+    padding-left: 2em;
+    padding-right: 0;
+  }
+
+  .layout-region-node-secondary {
+    float: right; /* LTR */
+    width: 35%;
+  }
+
+  [dir="rtl"] .layout-region-node-secondary {
+    float: left;
+  }
+
+  /* @todo File an issue to add a standard class to all text-like inputs */
+  .layout-region-node-secondary .form-autocomplete,
+  .layout-region-node-secondary .form-text,
+  .layout-region-node-secondary .form-tel,
+  .layout-region-node-secondary .form-email,
+  .layout-region-node-secondary .form-url,
+  .layout-region-node-secondary .form-search,
+  .layout-region-node-secondary .form-number,
+  .layout-region-node-secondary .form-color,
+  .layout-region-node-secondary textarea {
+    box-sizing: border-box;
+    width: 100%;
+    max-width: 100%;
+  }
+}
+
+/**
+ * The vertical toolbar mode gets triggered for narrow screens, which throws off
+ * the intent of media queries written for the viewport width. When the vertical
+ * toolbar is on, we need to suppress layout for the original media width + the
+ * toolbar width (240px). In this case, 240px + 780px.
+ */
+@media screen and (max-width: 1020px) {
+  .toolbar-vertical.toolbar-tray-open .layout-region-node-main,
+  .toolbar-vertical.toolbar-tray-open .layout-region-node-footer,
+  .toolbar-vertical.toolbar-tray-open .layout-region-node-secondary {
+    float: none;
+    width: auto;
+    padding-right: 0;
+  }
+}
+
+/* Node preview container. */
+.node-preview-container {
+  position: fixed;
+  z-index: 499;
+  width: 100%;
+  padding: 10px;
+}
+
+@media only screen and (min-width: 36em) {
+  .node-preview-container .form-type-select {
+    margin-left: 25%; /* LTR */
+  }
+  [dir="rtl"] .node-preview-container .form-type-select {
+    margin-right: 25%;
+    margin-left: 0;
+  }
+}
+
+/* Revision color. */
+.revision-current {
+  background: #ffc;
+}